#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	int a,b,c;
	cin >> a >> b >> c;
	if(b == 0){
		cout << "0" << endl;
	}else{
		int result = ceil(c * 1.0 / b);
		int shengyu = a - result;
		if(shengyu <= 0){
			cout << "0" << endl;
		}else{
			cout << shengyu << endl;
		}
	}
	
	return 0;	
} 
